Their objective: to collect samples of the Taylor oil slick for analysis, to see if it’s chemically distinguishable from the oil that gushed from BP’s infamous Macondo well about 30 miles away. We wanted to know if other samples of oil collected in this region of the Gulf, on beaches and barrier islands and from slicks observed offshore, could possibly be coming from the Taylor site since it’s a well-documented source of oil pollution. The NWF team — coached in advance by Dr. Ed Overton at Louisiana State University on proper collection and sampling technique — succeeded. Dr. Overton analyzed the Taylor oil samples and in mid-October told us “these were heavily weathered oil with slight differences in the fingerprint pattern from the Macondo oil.” (more after the jump….)

Elaborating on this a few days later, Dr. Overton said “the biomarker fingerprint is very similar but it does have significant differences especially in the 218 and 231 ion plots. Also, the C2DBT/C2Ph and C3DBT/C3Ph ratios are not consistent with Macondo oil. The sample we got from Ben Raines [of a small slick one mile from the Macondo well location] was very fresh with almost no weathering while the Taylor samples were all pretty heavily weathered with almost no normal hydrocarbons left in the GC data. So, if you know what you are doing, you should be able to distinguish between Taylor sheens and other samples especially of the Macondo oils. We really need samples of nearby seep oils and sheens from these seeps to get a full picture but so far, we have been able to fingerprint the Macondo oil fairly accurately (at least in my opinion).”

Here is a graphic Dr. Overton provided us yesterday, illustrating the difference in “weathering” of the Taylor oil samples from NWF compared with fresh Macondo oil samples taken directly from the riser pipe that connected the Macondo well with the Deepwater Horizon platform. Dr. Overton said “While the data shown in the plots are not from the fingerprinting, these plots clearly show how much the Taylor samples were weathered compared to the Macondo Riser oil. Getting good samples of all the slicks is a very daunting task because it requires close collaboration between surface sampling vessels and airborne observation. None the less, we still do not have good samples from sheens in the vicinity of the Macondo well.”

Data illustrating difference in weathering between oil samples taken from slicks at the Taylor/23051 chronic leak site, and from the riser pipe containing fresh crude from the Macondo well. Graphic courtesy Dr. Ed Overton, Louisiana State University.

The upshot: oil leaking from the Taylor site should not easily be confused with relatively unweathered oil from the Macondo disaster. But it would be very helpful to collect more and better samples from the slicks being observed in the vicinity of the Macondo well site.

Eventually, as residual Macondo oil gets older and more highly weathered it will become more difficult to differentiate it from Taylor oil.

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